Positioning mechanism

ABSTRACT

The disclosed embodiment of the present invention is a mechanism for positioning the CRT (cathode ray tube) at the object plane of an optical system, thereby permitting focusing of the image projected by the system. A plate for supporting the CRT is provided with a notch in an edge parallel to the direction of travel of the plate. The CRT plate is supported by a mounting surface which contains a row of offset holes in such a position that they align with the notch when the CRT plate is installed thereon. A camming tool having a shaft with an eccentric member mounted thereon and a handle disposed for manual rotation thereof is provided for effecting relative motion between the CRT plate and the mounting surface. The diameter of the eccentric member attached to the shaft of the camming tool is substantially equal to the width of the notch in the edge of the CRT plate, and the diameter of the shaft of the camming tool is substantially equal to the diameter of the holes in the mounting surface. In use, the shaft of the camming tool is inserted into one of the holes in the mounting surface, such that the eccentric member is received within the notch. Rotation of the camming tool imparts a force on the CRT plate which, in turn, displaces the CRT along the optical axis.

United States Patent Laughlin [151 3,692,268 5] Sept. 19, 1972POSITIONING MECHANISM [72] Inventor: Gerald J. Laughlin, Palo Alto,Calif.

[73] Assignee: The Singer Company, New York,

22 Filed: Feb.3, 1971 211 Appl.No.: 112,200

[52] US. Cl. ..248/346, 248/23, 269/66, 269/321 T [51] Int. Cl. .iFl6m13/00, HOSk 13/00 [58] Field of Search ..248/346, 23; 108/102, 143;269/66, 321 A, 321 T, 58, 59

[56] References Cited UNITED STATES PATENTS 406,828 7/1889 Fietsch..269/32l ME 2,778,235 1/1957 Amonsen ..248/23 X 3,408,924 11/1968Mueller ..269l321 ME 3,074,177 1/1963 Duroisin ..'...248/23 X PrimaryExaminer-Chancellor E. Harris Attorney-Francis L. Masselle, WilliamGrobman and Andrew G. Pullos ABSTRACT The disclosed embodiment of thepresent invention is a mechanism for positioning the CRT (cathode raytube) at the object plane of an optical system, thereby permittingfocusing of the image projected by the system. A plate for supportingthe CRT is provided with a notch in an edge parallel to the direction oftravel of the plate. The CRT plate is supported by a mounting surfacewhich contains a row of offset holes in such a position that they alignwith the notch when the CRT plate is installed thereon. A camming toolhaving a shaft with an eccentric member mounted thereon and a handledisposed for manual rotation thereof is provided for effecting relativemotion between the CRT plate and the mounting surface. The diameter ofthe eccentric member attached to the shaft of the camming tool issubstantially equal to the width of the notch in the edge of the CRTplate, and the diameter of the shaft of the camming tool issubstantially equal to the diameter of the holes in the mountingsurface. In use, the shaft of the camming tool is inserted into one ofthe holes in the mounting surface, such that the eccentric member isreceived within the notch. Rotation of the camming tool imparts a forceon the CRT plate which, in turn, displaces the CRT along the opticalaxis.

4 Claims, 3 Drawing Figures PATENTED 19 I973 3.692.268

Fig.3

INVENTOR. Fig 2 GERALD J. LAUGHLIN POSITIONING MECHANISM This inventionrelates generally to positioning mechanisms and more particularly to amechanism for positioning, along the optical axis, an image on the faceof a CRT disposed in an optical system to thereby focus said image.

In the past, positioning of a CRT for purposes of focusing an imagethereon employed an adjusting screw which was operated by a knurledknob. To move a CRT employing an adjusting screw requires many turns ofthe knurled knob to move only a small distance. This precise positioningmechanism was slow and tedious.

The positioning of a CRT by the use of an adjusting screw and knurledknob can often be substantially inaccessible' for operation. Anadjusting screw must operate directly on the element to be positioned,and the knurled knob must be connected directly to the adjusting screw.This requirement usually places the knurled knob in a location difficultfor an operator to reach.

The use of an adjusting screw as a positioning mechanism requirescareful realignment each time the CRT was removed and replaced. Also,the parts employed in an adjusting screw mechanism were expensivebecause accurate machining of many small parts was required.Accordingly, it is an object of the present invention to provide apositioning mechanism which offers ease of operation while permittingrelatively fine adjustment.

It is another object of the present invention to provide a mechanismwhich can accurately position a CRT rapidly.

Another object of the present invention is to provide a camming toolwith a handle for operation constructed to a length convenient foraccessibility.

Still another object of the present invention is to provide apositioning mechanism that requires no critical realignment followingremoval and replacement of the CRT.

It is still a further object of the present invention to provide apositioning mechanism that is simple and inexpensive to construct. A

A feature of the present invention resides in the provision of a cammingsurface, formed in the disclosed exemplification of the presentinvention of a notch in an edge of a plate, and a plurality of holeshaving a predetermined positional relationship to the camming surfaceand permit fine, but relatively rapid and easy, adjustment of the plate.

These and other objects, features and advantages of the presentinvention will be more fully realized and understood in the followingdetailed description, wherein:

FIG. 1 is a perspective view, partly cut away, showing a positioningmechanism for a CRT constructed in accordance with the principles of thepresent invention;

FIG. 2 is a partial plan view of the CRT plate and mounting surfaceparticularly showing the slot in the CRT plate and the row of holes inthe mounting surface in alignment therewith;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1 showing thecamming tool in alignment with the CRT plate and mounting surface.

With reference to the drawings in detail and in particular to FIG. 1,there is shown a cathode ray tube (CRT) which is mounted in an opticalsystem (not shown) with the longitudinal axis 12 thereof being Stillanother feature of the present invention resides vantage of permittingrelatively fine adjustment between two members, such as a CRT plate anda mounting surface therefor. Furthermore, such fine adjustment can bemade using the present invention with relative ease by an operator. Thisadvantage is further enhanced by the relatively short time required toperform the adjustment.

coincident with the optical axis of the optical system. The base plate14 which is integral with the supporting structure of the optical systemforms a mounting surface for the CRT 10 and its associated supportingstructure. The CRT 10 is supported along its length by members 16, 18and 20, which members extend from and are rigidly secured to a plate 22.

The CRT base plate 22 is mounted on the optics base plate 14 by means ofbolts 24, 26 and 28 which extend through slots 30, 32 and 34,respectively, in the plate 22 and threadably engage the plate 14. Theelongated slots 30, 32 and 34 permit relative motion between the CRTbase plate 22 and the optics plate 14 along the axis 12. v

The position of the CRT base plate 22 with respect to the optics baseplate 14 along a direction orthogonal to the axis 12 is accuratelymaintained by alignment blocks 36 and 38 engaging a edge 40 of the baseplate 22 and by an alignment block 42 engaging a edge 44 of the baseplate 22. Accordingly, it can be appreciated that the CRT 10 and itsassociated supporting structure can be positioned along the axis 12 byloosening the bolts 24, 26 and 28, moving the plate 22 with respect tothe optics base plate 14 to the desired position, and tightening thebolts to maintain the desired position. It will be appreciated that anylateral movement will be restrained by the alignment blocks 36, 38 and42. The position of the CRT 10 can be refined for accurate focusingwithin the optical system by employing the positioning mechanism of thepresent invention.

A notch 46 is provided at one edge of the CRT base plate 22, withopposite sides 48 and 50 of the notch forming camming surfaces which areorthogonal to the axis 12. A plurality of holes 52 are provided in theoptics base plate 14 which align with the slot 46. A plan view of thealignment of the holes 52 with respect to the notch 46 is better shownin FIG. 2.

The holes 52 are arranged in two rows, with each row extending in thedirection of the desired path of displacement of the plate 52 withrespect to the plate 14. The centers of the holes in one row are equaldistance between adjacent pairs of holes in the next row. As will beappreciated from the description of FIG. 3, the maximum distance betweenthe centers of the holes is a critical dimension.

As shown in FIG. 3, a camming tool, generally designated with thereference numeral 54 is provided for effecting relative motion betweenthe CRT plate 22 and the optics base plate 14 and includes a shaft 56for engaging individual holes of the plurality of holes 52 and aneccentric member 58 mounted on the shaft 52 with a handle 60 extendingtherefrom for manual rotation thereof. The eccentric member is circularin structure to prevent any backlash while positioning the CRT plate.ln-operation, the camming tool shaft 56 is inserted into an individualhole 52a which is aligned with the notch 46 as shown in the sectionalview of FIG. 3. With the camming tool 54 in the position shown in FIG.3, rotation of the handle 60 imparts a force on the camming surface 50by virtue of the rotation of the eccentric member 58. This force, inturn, causes a displacement of the CRT base plate 22 to the right asshown in the drawing.

If it is desired to continue movement of the CRT plate 22 in a directionto the right, as shown in FIG. 3, after the above described displacementis effected, the shaft 56 is inserted into a subsequent hole and thetool 54 is again rotated. However, if such displacement is not effected,the shaft 56 can be inserted into a hole 52c and subsequent rotation ofthe handle 60 would move the CRT plate 22 to the left as shown in thedrawing. The maximum distance the CRT plate 22 can travel with oneinsertion of the camming tool is equal to twice the distance theeccentric member 58 is offset from the shaft 56. The distance the CRTplate 22 is displaced, or twice the offset distance, is defined as thedifferential of the eccentric member 58.

The individual adjacentholes in the plurality of holes 52 are offset onefrom the other, and are disposed along an axis parallel to the opticalaxis a distance equal to or less than the differential of the eccentricmember 58. More particularly, the holes 52 in a preferred embodiment aredisposed a distance substantially less than the differential of theeccentric member to provide ease of inserting the tool 54 intorespective member mounted thereon for engaging said camming surface,said means including individual means for engaging said shaft andrestraining movement thereof in one direction opposed to the directionof the force on said camming surface exerted by said camming tool,adjacent ones ofsaid individual means being positioned relative to oneanother a distance at least equal to the differential of said eccentricmember.

2. A mechanism as defined in claim 1 wherein said notch is located in anedge parallel to the direction of travel of said plate.

3. A mechanism as definedin claim 2 wherein the width of said notch issubstantially equal to the diameter of said ecce tric rn ber f r e a inth reof. 4. A mechanism as defined in claim 1 for focusing an image onthe face of a CRT' disposed in an optical system, wherein said CRT ismounted on said plate, and the individual means being formed of aplurality of holes in said mounting surface for engaging said shaft.

. a camming tool having shaft with an eccentric

1. A positioning apparatus comprising: a. a plate having a notch in oneedge forming a camming surface; b. means forming a surface for mountingsaid plate for slidable movement thereon in a direction orthogonal tothat of said camming surface; and c. a camming tool having shaft with aneccentric member mounted thereon for engaging said camming surface, saidmeans including individual means for engaging said shaft and restrainingmovement thereof in one direction opposed to the direction of the forceon said camming surface exerted by said camming tool, adjacent ones ofsaid individual means being positioned relative to one another adistance at least equal to the differential of said eccentric member. 2.A mechanism as defined in claim 1 wherein said notch is located in anedge parallel to the direction of travel of said plate.
 3. A mechanismas defined in claim 2 wherein the width of said notch is substantiallyequal to the diameter of said eccentric member for engaging thereof. 4.A mechanism as defined in claim 1 for focusing an image on the face of aCRT disposed in an optical system, wherein said CRT is mounted on saidplate, and the individual means being formed of a plurality of holes insaid mounting surface for engaging said shaft.